The reported results confirm that the presence of positively charged groups on porphyrin frame is fundamental for PSs antibacterial activity, however our data suggest that a moderate degree of lipophilicity, achievable by the introduction of aromatic hydrocarbon side chains on the pyridyl moieties, may improve PSs efficiency. Furthermore dicationic porphyrin 7 seems to be more efficient than the corresponding tetracationic derivatives thus emphasizing an interesting feature involved in the PSs activity.

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Photodynamic therapy (PDT) is a cancer treatment involving systemic administration of a tumor-localizing photosensitizer; this, when activated by the appropriate wavelength of light, interacts with molecular oxygen to form a toxic, short-lived species known as singlet oxygen, which is thought to mediate cellular death. Photofrin, a complex mixture of porphyrin oligomers has recently received FDA approval for the photodynamic treatment of esophageal and endobronchial carcinoma, but its photodynamic and toxicity profiles are far from ideal. In the present study we evaluated a series of porphyrin-based PSs, some of which newly synthesized by our group, with the aim to identify agents with more favorable characteristics. For the most effective compounds in the porphyrin series, chlorin analogs were also synthesized; for comparison, the screening also included Photofrin. Cytotoxicity studies were performed by the MTT assay on a cultured human colon adenocarcinoma cell line (HCT116); the results indicate that the 3,4,5-trimethoxyphenyl, 3OH- and 4OH-phenyl, and the sulfonamidophenyl derivatives are significantly more potent than Photofrin. Flow cytometric studies and fluorescence microscopy indicate that in PDT-treated HCT116 cells death occurs mainly by apoptosis. In summary, novel PSs described in the present study, belonging both to the porphyrin and chlorin series, have proven more effective than Photofrin in killing colon cancer cells in vitro; extending these observation to in vivo models, particularly regarding the deeper reaching chlorin derivatives, might lead to significant advances in the development of tumor PDT.

Five long bis(4-pyridyl) ligands with different tether groups, namely 1,4-phenylenebis(4-pyridylmethanone) (L 1 ), bis(4-pyridyl)terephthalate (L 2 ), 1,5-bis(pyridin-4-ylmethoxy)naphthalene (L 3 ), 1,4-bis[2-(4-pyridyl)ethenyl]benzene (L 4 ) and 4,4Ј-bis(pyridin-4-ylmethoxy)biphenyl (L 5 ), have been synthesized and employed for the self-assembly of coordination polymers and architectures, with the aim of obtaining structural motifs characterized by long metalmetal separations. Six coordination products (compounds 1-6) have been obtained by reacting the ligands with cobalt() nitrate in all cases but one, in which zinc() triflate was used. The crystal structures show a variety of structural motifs. [Co(L 2 )(NO 3 ) 2 (MeCN)]ؒMeCN (2) and [Co(L 5 )(NO 3 ) 2 ] (5) contain one-dimensional polymeric chains (linear, with a period of 19.64 Å in 2; zigzag, with a period of 38.65 Å in 5).exhibit extended three-dimensional and two-dimensional arrays, respectively, sustained both by coordinative and hydrogen bonds. Compound 3, [Co(L 3 ) 2 (NO 3 ) 2 ]ؒ(CH 2 Cl 2 ) 2 , consists of two-dimensional layers of large rhombic meshes (diagonals of the rhombus 15.43 and 35.74 Å), while compound 6, [Co 2 (L 5 ) 4 (NO 3 ) 4 ]ؒ(Me 2 CO) 2 , contains discrete dinuclear molecules, consisting of large rings with appendages, which exhibit an exceptionally long dimension of 62.84 Å and form columnar supramolecular arrays.

A series of 39 boron-dipyrrolylmethenes (BODIPYs) have been synthesized and characterized. Their spectroscopic properties, degree of lipophilicity, chemical stability under irradiation, and singlet-oxygen generation rate have also been studied. These compounds differ in the presence of ethyl groups (group A), hydrogens (group B) or iodines (group C) on the 2,6 positions; these appendices confer particular characteristics to each group. The presence of an aromatic substituent or hydrogen on the indacene 8 position produces 13 different molecules of each group. Besides the effects exerted by the group or atom on the 2,6 positions, the substituent on the 8 position exerts a further effect on the physico-chemical parameters, thus the desired properties of BODIPYs, concerning fluorescence, lipophilicity, and singlet oxygen production can be modulated accordingly

The synthesis of a panel of seven nonsymmetric 5,10,15,20-tetraarylporphyrins, 13 symmetric and nonsymmetric 5,15-diarylporphyrins, and one 5,15-diarylchlorin is described. In vitro photodynamic activities on HCT116 human colon adenocarcinoma cells were evaluated by standard cytotoxicity assays. A predictive quantitative structure-activity relationship (QSAR) regression model, based on theoretical holistic molecular descriptors, of a series of 34 tetrapyrrolic photosensitizers (PSs), including the 24 compounds synthesized in this work, was developed to describe the relationship between structural features and photodynamic activity. The present study demonstrates that structural features significantly influence the photodynamic activity of tetrapyrrolic derivatives: diaryl compounds were more active with respect to the tetraarylporphyrins, and among the diaryl derivatives, hydroxy-substituted compounds were more effective than the corresponding methoxy-substituted ones. Furthermore, three monoarylporphyrins, isolated as byproducts during diarylporphyrin synthesis, were considered for both photodynamic and QSAR studies; surprisingly they were found to be particularly active photosensitizers.

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